On 10/03/2017 12:23 AM, Jeff Law wrote:
> On 09/20/2017 12:04 PM, Martin Sebor wrote:
>> On 09/19/2017 03:00 PM, Joseph Myers wrote:
>>> On Tue, 19 Sep 2017, Martin Sebor wrote:
>>>
>>>>> In general, the data structures where you need to ensure manually that if
>>>>>
>>>>> attribute A is listed in EXCL for B, then attribute B is also listed in
>>>>> EXCL for A, seem concerning. I'd expect either data structures that make
>>>>>
>>>>> such asymmetry impossible, or a self-test that verifies that the tables in
>>>>>
>>>>> use are in fact symmetric (unless there is some reason the symmetry is not
>>>>>
>>>>> in fact required and symmetric diagnostics still result from asymmetric
>>>>> tables - in which case the various combinations and orderings of
>>>>> gnu_inline and noinline definitely need tests to show that the diagnostics
>>>>>
>>>>> work).
>>>>
>>>> If I understand correctly what you're concerned about then I don't
>>>> think there are any such cases in the updated version of the patch.
>>>
>>> I don't see how you ensure that it's not possible to have such asymmetry.
>>> My point wasn't so much "there was a bug in the previous patch version" as
>>>
>>> "the choice of data structures for defining such exclusions is prone to
>>> such bugs". Which can be addressed either by using different data
>>> structures (e.g. listing incompatible pairs in a single array) or by a
>>> self-test to verify symmetry so a compiler with asymmetry doesn't build.
>>
>> Okay, that's a useful thing to add. It exposed a couple of missing
>> attribute exclusions that I had overlooked. Thanks for the suggestion!
>> Attached is an incremental diff with just these changes to make review
>> easier and an updated patch.
>>
>> As an aside, there are a number of other possible logic errors in
>> the attribute specifications that could be detected by self-tests.
>> The one I ran into is misspelled attribute names. The added test
>> detects misspelled names in exclusions, but not in the main specs.
>>
>> Martin
>>
>> gcc-81544-1-inc.diff
>>
>>
>
>
>> gcc-81544-1.diff
>>
>>
>> PR c/81544 - attribute noreturn and warn_unused_result on the same function
>> accepted
>>
>> gcc/c/ChangeLog:
>>
>> PR c/81544
>> * c-decl.c (c_decl_attributes): Look up existing declaration and
>> pass it to decl_attributes.
>>
>> gcc/c-family/ChangeLog:
>>
>> PR c/81544
>> * c-attribs.c (attr_aligned_exclusions): New array.
>> (attr_alloc_exclusions, attr_cold_hot_exclusions): Same.
>> (attr_common_exclusions, attr_const_pure_exclusions): Same.
>> (attr_gnu_inline_exclusions, attr_inline_exclusions): Same.
>> (attr_noreturn_exclusions, attr_returns_twice_exclusions): Same.
>> (attr_warn_unused_result_exclusions): Same.
>> (handle_hot_attribute, handle_cold_attribute): Simplify.
>> (handle_const_attribute): Warn on function returning void.
>> (handle_pure_attribute): Same.
>> * c-warn.c (diagnose_mismatched_attributes): Simplify.
>>
>> gcc/ChangeLog:
>>
>> PR c/81544
>> * attribs.c (empty_attribute_table): Initialize new member of
>> struct attribute_spec.
>> (decl_attributes): Add argument. Handle mutually exclusive
>> combinations of attributes.
>> * attribs.h (decl_attributes): Add default argument.
>> * selftest.h (attribute_c_tests): Declare.
>> * selftest-run-tests.c (selftest::run_tests): Call attribute_c_tests.
>> * tree-core.h (attribute_spec::exclusions, exclude): New type and
>> member.
>> * doc/extend.texi (Common Function Attributes): Update const and pure.
>>
>> gcc/testsuite/ChangeLog:
>>
>> PR c/81544
>> * c-c++-common/Wattributes-2.c: New test.
>> * c-c++-common/Wattributes.c: New test.
>> * c-c++-common/attributes-3.c: Adjust.
>> * gcc.dg/attr-noinline.c: Adjust.
>> * gcc.dg/pr44964.c: Same.
>> * gcc.dg/torture/pr42363.c: Same.
>> * gcc.dg/tree-ssa/ssa-ccp-2.c: Same.
> OK.
> jeff
>
On targets enforcing a function alignment bigger than 4 bytes this triggers an
error instead:
+inline int ATTR ((aligned (4)))
+finline_hot_noret_align (int); /* { dg-warning "ignoring attribute .aligned
\\(4\\). because it
conflicts with attribute .aligned \\(8\\)." } */
gcc/gcc/testsuite/c-c++-common/Wattributes.c:404:1: error: alignment for
'finline_hot_noret_align'
must be at least 8^M
